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FILE - In this Sept. 2007 file picture an anti-aircraft gun position is seen at Iran's nuclear enrichment facility in Natanz, Iran. Iran has put finishing touches for the installation of thousands of new-generation machines at a cavernous underground bunker that would allow it speed up production of material that can be used to arm nuclear warheads, diplomats tell The Associated Press, Saturday, Feb. 18, 2012. While saying that the electrical circuitry, piping and supporting equipment for the new centrifuges was in place, the diplomats emphasized that Tehran had not started installing more efficient centrifuges at its Fordow facilty and could not say whether it was planning to. (AP Photo/Hasan Sarbakhshian, File)
/ AP